Heretofore, a non-volatile memory using a phase-change film has been known which is described specifically, for example, in Patent Document 1. This is a phase-change memory in which memory information is written by the change of the state of crystallization of a memory device in accordance with a Joule heat caused by current flowing through the memory device per se. Since a recording layer is once melted at a temperature exceeding 600° C. by Joule heat upon amorphization, while the write current tends to be increased, the resistance value changes as much as from two digits to three digits in accordance with the state of crystallization. Since the resistance value is used as the signal in the memory, a read signal is large and the sensing operation is easy.
FIG. 2 is a schematic diagram illustrating the constitution of a phase-change memory in FIG. 12 of Patent Document 1. The phase-change memory comprises a memory array, a row decoder XDEC, a column decoder YDEC, a read circuit RC, and a write circuit WC. In the memory array, a memory cell MCpr is disposed at each of intersections of word lines WLp (p=1, - - - , n) and data lines DLr (r=1, - - - , m). Each memory cell has a constitution in which a memory device RM and a select transistor QM connected in series are inserted between the data line DL and the ground potential. The word line WL is connected to the gate of the select transistor, and the column select line YSr (r=1, - - - , m) is connected to a corresponding column select switch QAr.
With the constitution described above, the select transistor on the word line selected by the row decoder XDEC is in conduction and a column select switch corresponding to the column select line selected by the column decoder YDEC is in conduction, whereby a current channel is created in the select memory cell to generate a read signal on the common data line I/O. Since the resistance value in the selected memory cell is different depending on the memory information, the voltage outputted to the common data line I/O results in a difference depending on the memory information. By discriminating the difference in the read circuit RC, the memory information in the select memory cell is read out.
On the other hand, Patent Document 2 describes a memory material used for an electric memory device including transition metal elements. While the transition metal elements do not contain, in most cases, the group 2b in the existent definition, the group 2b is also defined as the transition metal element in this specification. Those containing 10 at % or less of Ti, etc. in a Ge—Sb—Te series material are described in the example.
Further, composition materials for use in a DVD recording surface are described in Patent Document 3, etc.    Patent Document 1: U.S. Pat. No. 5,883,827 specification    Patent Document 2: JP-A No. 2001-502848    Patent Document 3: JP-A No. 2003-081724    Non-Patent Document 1: IEEE International Electron Devices Meeting, TECHNICAL DIGEST, 2001, p. 803-806